He was restrained by a passenger on another flight, who held him down on a chair near the gate before police arrived within five minutes, they told the Herald.
“He was holding him down on the chair, and then another one [member of the public] was trying to talk him out of doing what he was doing.”
Security personnel were also present, the witness said.
The man was handcuffed by police, who took him to the bathrooms, they said.
The witness, who did not wish to be named, said the man did not appear to be well.
About half of the passengers were already on the Air New Zealand flight, which was destined for Wellington, they said.
The incident was over quickly and did not cause much of a delay, the witness said.
Police told the Herald a 33-year-old man has been taken into custody after an incident of offensive behaviour at Auckland Airport.
Auckland Airport said it can confirm police and airport security attended an incident at the domestic terminal yesterday evening.
“There was no impact to arriving or departing flights.”
Air New Zealand did not wish to comment.